[C320-list] Blade falls off of Autoprop propeller!

[Robert E. Sloat]

Check out their website at http://ab-marine.com/.  There is all kind of 
installation information and
maintenance procedures for the various model Autoprop propellers.  Mine is 
the H5 model which does not require any greasing.  For the models which 
require greasing, they suggest every 2 years.  The installation instructions 
for my prop suggest rotating the blades at haul out to make sure they freely 
move and gives information on bearing replacement kits when needed.



----- Original Message ----- 
From: "WindSwept" <c320_windswept at sbcglobal.net>
To: "'C320-List'" <C320-List at catalina320.com>
Sent: Saturday, September 09, 2006 8:59 AM
Subject: [C320-list] Blade falls off of Autoprop propeller!


A funny thing happened on the way to the ship yard this spring for my
semi-annual bottom job.  Well maybe not so funny.

Carla and I spent the night at anchor in a cove about 1/2 mile from the yard
the prior to dropping off WindSwept.

After hauling anchor when we tried to motor over to the yard the boat shook
terribly at any RPMs above idle.

We quickly anchored again and I dove below the boat to find out what was
wrapped around the prop, but was amazed to find that one of the three blades
of my Autoprop was just......missing!

We managed to sail to the yard which is located up a narrow channel and moor
in the haul up slip.  Luckily the wind was from a favorable direction.

To make a long story shorter, I had the fixed three blade that came with
WindSwept reinstalled and sent the Autoprop to AB Marine for analysis and
repair.  The prop had to be sent back to the factory in the UK so the
engineers could look at it and a new blade could be fabricated.

The reason for the failure was that the bearings were excessively worn
causing too much torque to be applied on the mechanical fastenings that hold
the blades on.

At this point I think it is relevant to mention that I had purchased the
Autoprop used about 7-8 years ago from a 320 owner who had traded up.  I do
not believe I received all the paperwork that one would normally receive
with a new Autoprop.  This paperwork discusses the need to inspect and
adjust the bearings at each haulout.  AB Marine sells a kit for this
purpose.

I was upset with AB Marine as through the years I have had many discussions
on this subject and even though I asked about maintenance, this was never
mentioned.  In their defense, they probably thought I had the original
instruction sheets for installation and maintenance.  As an engineer I was
amazed that I didn't need to do any maintenance on a bearing in this type of
service.  The autoprop had been on WindSwept for four years without
maintenance before the failure occurred.

The point of all this is that I think this was a preventable situation had I
know to inspect the bearings for excessive looseness and adjust every year
or two as needed.

I plan on having the Autoprop put back on in a couple of weeks as I can
definitely say it really improves boat speed and handling in all situations.
I will inspect it annually and disassemble and adjust bearing clearances
every other year at a minimum.

I wanted to share my experience with others in the hopes that you don't
experience the same problem.  In another situation it could have been much
more disastrous.

Larry
WindSwept C320 #246